Improvement in direct-acting engines



UNITED STATES PATENT OEEIcEc WILLIAM J. STEVENS, on NEW YORK, N. Y.

IMPROVEMENT IN DIRECT-ACTING ENGINES.

Specification forming part of Letters Patent No. 109,963, dated December6, 1870.

To all lwhom it may concern Be it known that I, WILLIAM J. STEVENS, ofthe city of New York, in the county and State of New York, have inventedcertain newand useful Improvements in Direct-Acting Engines; and Ihereby declare that the following is a full, clear, and exactdescription thereof, reference being had to the accompanyin g drawing,which forms part of this speciiication.

My invention consists in a novel combination, in a direct-actingsteam-engine, of the main valves of a steam-cylinder with the piston ofan auxiliary or valve-operating cylinder by means of a rocking lever,the ends of which take hold of a stem connected to said valves and therod of said piston respectively, whereby a positive motion is insuredand unequal wear of the valves'is prevented.

My invention further consists in the combination of a main cylinder andauxiliary cylinder and said rocking lever with a regulatingchamber,whereby convenience of access to the auxiliary cylinder andregulating-chamber is insured.

My invention further consists in an improved arrangement of asteam-chamber in such relation to the auxiliary cylinder and to thesteamchamber of the main cylinder as to cheapen the construction of theparts and enable the valve of the auxiliary cylinder to work on ahorizontal seat.

My invention further consists in an improved means for adjusting theeffective length of the lever which operates the valve of the auxiliarycylinder, and thereby regulating the length of the stroke of the mainpiston.

In the accompanying drawing, Figure l represents a central verticallongitudinal section of a direct-acting steam-en gine embodying myimprovements. Fig. 2 is a vertical cross-section, in detail, of themeans employed for regulating the stroke of the main piston.

A designates the main cylinder; B, the' main piston moving therein, thelatter being, of course, provided with a piston-rod, C, passing througha suitable stufling-box, and being connected to that part of anapparatus which is to receive a direct reciprocating motion.

In the drawing I have shown said pistonrod C as connected directly tothe piston of a pump-cylinder, E, which cylinder is provided with propervalve-chambers F. These parts are all of well-known construction, andsteam is supplied to the steam-chest G of the main cylinder in anysuitable way-say through the opening or pipe a.

H I-I are the main valves, which are of the ordinary construction, andwhich operate in connection with the cylinder-port b c and anexhaust-passage, d, in the usual manner.

The main valves H are operated by a piston, l, of an auxiliary engine orcylinder, m, in the following manner: To the said piston Za pistonrod,k, is attached, and this piston-rod 7c is provided With a rack, t',which engages with a toothed segment, IL, on the upper end of a lever,J, which lever is pivoted at a suitable part of its len gth-say atl)'-to any stationary obj ect-th e valve-cylinder F, for instance. Atoothed segment, g, on the lower end ot' the lever J engages with therack f on the valve-stem c of the valves of the main cylinder, and movesthe latter in a direction opposite to that imparted to the upper end ofthe lever J by the piston Zot' the auxiliary cylinder.

Rollers a n, or other suitable guides, serve to keep the racks f and cin gear with the segments g and h. rIhe lever J may be provided withsimple pins in its ends, arranged to engage with or move in transverseslots in the rods k and e or pins projecting from the said rods k and emay engage with or move in slots in the end of said lever; or said levermay be connected to said rods bylinks or connections in an obviousmanner; but the arrangement I have shown I consider thel simpler, and itinvolves less friction.

Steam is admitted to the auxiliary cylinder m to operate the piston Z bymeans of the valve O, placed in a chest, (3f/,located between the saidcylinder m and the main steam-chest G, so as to communicate freely wit-hthe latter by means of a side pipe or passage.

The ports of the auxiliary cylinder m are Adesignated by the letters pand r, and they pass underneath the seat of the valve O outward to andupward through the Walls of the steam-chest G of the auxiliary cylinderto the ends of the cylinder m, and each port is alternately placed incommunication with the chest Gr' and the secondary exhaust-port el',

the latter connecting with the main exhaustpipe d by the valve O, whichvalve is a slidevalve of the ordinary construction.

The said valve O is operated by the main piston in the following manner:The stem of the said valve O is pivoted to a connectingrod, S, whichlatter is connected by a pin, to a lever, K, which lever is pendent froma swivel, which is secured to any suitable stationary objectforinstance, to arms which 'project from the steam-chest G; and thepiston-rod C is pivoted to the lower end of this lever K.

The manner of hanging the lever K forms the special subject of onefeature of my inltion, and a description thereof will be betterunderstood after I state briefly the operation of the mechanism thus fardescribed.

We will assume that the main valves H are at the left-hand extreme oftheir movement, the auxiliary piston Z at the right, and the main pistonB and valve O of the auxiliary cylinder in the position shown. Now, ifsteam be admitted through the opening or pipe a to the steam-chest G, itwill enter the cylinderport c and drive the piston B to the left untilthe piston-rod C', by means of lever K and rod s, moves the valve O inthe same direction-z'. e., to the left-when steam will enter theauxiliary cylinder m through port r and push the piston l to the left,and thereby, through rod 7c, lever J, and rod e, move the main valves tothe right, thus admitting steam to the main cylinder A through the portb on the left side of the piston, and permitting the steam on the rightof the piston B to escape to the exhaust-port d throughport c, andthereby cause the main piston to move to the right until the valve Oopens the port p, when the main valves are returned to the firstposition, and the operation is repeated.

The auxiliary valve O is provided with outside lapL-that is, it islonger than the distance between the outer edges of the cylinderports pand i" hence the main piston must necessarily move a sufticient distancepast its mid position to open one of the said ports before the mainvalves will be moved.

In order to regulate this distance on the stroke of the main piston,means are provided to lower or raise the lever K in the swivel w, so asto bring the point a; where the auxiliary valve-rod s connects fartherfrom or nearer to the fulcrum at the swivel w, thereby increasing ordecreasing the throw of the valve O, and admitting steam to theauxiliary cylinder to move the main valves sooner or later in the strokeof the main piston. To effect this regulation, the upper part of thelever K is provided, as shown in Fig. 2, with a screw-thread, whichpasses through the swivel w and enters a nut formed in the hub of thehand-wheel M. The said hub of the hand-wheel is secured t0 the swivel wby the screwcap g/ and ring z, as shown in Fig. 2, so that the wheelcannot be lifted off the swivel, but may be freely revolved, so as tomove the leverK up and down, and thus alter the throw of the valve O.

To regulate the movement of the piston lof the auxiliary cylinder andprevent it from striking its heads, I attach to the rod k of said pistonl a piston, u, moving in a regulatingcylinder, o. This cylinder isiilled with air, water, or other fluid, and, in one method ofconstruction, the piston u fit-s a little loose, so that the air orfluid is slowly displaced from one side of it to the other, thusretarding the motion of the auxiliary piston l.

By another plan the piston tits tightly; but the ends of the cylinderare connected nby a pipe provided with a stop-cock, to regulate thevelocity of the flow.

In a more approved mode of construction, a groove or counterbore, N,(shown in dotted lines,) is made in the interior of the cylinder, so asto extend from the center nearly to the ends. This latter constructionpermits the free movement of the piston at mid position but it iscushioned at either end on iiuid, which cannot escape after the pistonruns over the end of the groove.

In direct acting steam-engines as heretofore constructed thevalve-operating pistons have usually been connected to the valves at aconsiderable distance from their seats, which causes unequal wear ontheir faces.

In the above arrangement I operate the valves by a stem placed as nearthe face as is usual in engines having a crank movement, and by means ofthe lever J shown I am enabled to place t-he auxiliary and regulatingcylinders at the upper part of the apparatus, where they are accessibleand have sufficient room for freedom of operation.

By the use of the lever J, having arms of unequal length, I am enabled,also, to give any desired length of stroke to the auxiliary piston for agiven throw to the main valves. By making the lower part of theauxiliary cylinder so that it forms the steam-chest of the auxiliaryvalve, I save in parts andl gain the additional advantage of providingahorizontal seat for the said valve.

It is of the greatest importance in using direct-acting engines to beable to regulate the time at which the steam is admitted to change thedirection of the main piston. If the engine be running slowly, the steamneed not be introduced till near the end of the stroke, but at highspeeds the piston acquires so much momentum that it will strike thecylinderheads unless cheeked by the admission of steam considerablybefore the end of the stroke. This can be readily accomplished when theengine is in motion by turning the hand-wheel M.

The adjustment is useful, also, in some cases to reduce the stroke ofthe engine at moderate speeds, as is often required vin drilling-engines and sometimes in pumps.

In Patent No. 44,232, granted to me September 13, 1864, I have shown amethod of regulatin g the stroke of t-he pump, in which a block is movedup and down in a slot in the valveoperating lever. The arrangementherein described is superior, for the reason that the adjusting-Wheel Mis nearer the fulcrum, and therefore derives less motion from the leverK, so that the stroke is more readily adjusted when the pump is in rapidmotion. It also gives the auxiliary valve a motion coincident with thatof the main piston, while the first plan reverses it, and wouldtherefore be inapplicable in many cases.

What I claim as my invention, and desire to secure by Letters Patent,is-

l.A The combination ofthe auxiliary cylinder, rocking lever, and mainvalves of a direct-acting vsteam-engine, substantially as and for thepurpose herein specied.

2. The combination of the regulating-cham- WV. J. STEVENS.

Witnesses:

M. M. LIvINGsToN, T. B. BEECHER.

